diff options
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 64 |
1 files changed, 28 insertions, 36 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 66338c4f7f4b..3f28192b420b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5028,6 +5028,8 @@ static __init int tracer_init_debugfs(void) trace_access_lock_init(); d_tracer = tracing_init_dentry(); + if (!d_tracer) + return 0; trace_create_file("trace_options", 0644, d_tracer, NULL, &tracing_iter_fops); @@ -5166,36 +5168,32 @@ void trace_init_global_iter(struct trace_iterator *iter) iter->cpu_file = TRACE_PIPE_ALL_CPU; } -static void -__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode) +void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { - static arch_spinlock_t ftrace_dump_lock = - (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; /* use static because iter can be a bit big for the stack */ static struct trace_iterator iter; + static atomic_t dump_running; unsigned int old_userobj; - static int dump_ran; unsigned long flags; int cnt = 0, cpu; - /* only one dump */ - local_irq_save(flags); - arch_spin_lock(&ftrace_dump_lock); - if (dump_ran) - goto out; - - dump_ran = 1; + /* Only allow one dump user at a time. */ + if (atomic_inc_return(&dump_running) != 1) { + atomic_dec(&dump_running); + return; + } + /* + * Always turn off tracing when we dump. + * We don't need to show trace output of what happens + * between multiple crashes. + * + * If the user does a sysrq-z, then they can re-enable + * tracing with echo 1 > tracing_on. + */ tracing_off(); - /* Did function tracer already get disabled? */ - if (ftrace_is_dead()) { - printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n"); - printk("# MAY BE MISSING FUNCTION EVENTS\n"); - } - - if (disable_tracing) - ftrace_kill(); + local_irq_save(flags); /* Simulate the iterator */ trace_init_global_iter(&iter); @@ -5225,6 +5223,12 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode) printk(KERN_TRACE "Dumping ftrace buffer:\n"); + /* Did function tracer already get disabled? */ + if (ftrace_is_dead()) { + printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n"); + printk("# MAY BE MISSING FUNCTION EVENTS\n"); + } + /* * We need to stop all tracing on all CPUS to read the * the next buffer. This is a bit expensive, but is @@ -5264,26 +5268,14 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode) printk(KERN_TRACE "---------------------------------\n"); out_enable: - /* Re-enable tracing if requested */ - if (!disable_tracing) { - trace_flags |= old_userobj; + trace_flags |= old_userobj; - for_each_tracing_cpu(cpu) { - atomic_dec(&iter.tr->data[cpu]->disabled); - } - tracing_on(); + for_each_tracing_cpu(cpu) { + atomic_dec(&iter.tr->data[cpu]->disabled); } - - out: - arch_spin_unlock(&ftrace_dump_lock); + atomic_dec(&dump_running); local_irq_restore(flags); } - -/* By default: disable tracing after the dump */ -void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) -{ - __ftrace_dump(true, oops_dump_mode); -} EXPORT_SYMBOL_GPL(ftrace_dump); __init static int tracer_alloc_buffers(void) |